There are plenty uses in fatty alkyl esters of vegetable oil, animal oils and marine oils. They are widely used as industrial fluids, especially as lubricants in the metal working industry, as base oil for drilling muds, industrial solvents, as carriers for the active ingredients in pesticides formulation and as diesel fuels. The advantages of the metyl esters such as low cost, lower toxicity and environmental friendliness have made the methyl esters a more preferable choice to be used in the above freezing point of water has restricted their many uses at low temperatures causing poor pumpability, precipitation and pourability of the esters during cold season. Palm oil alkyl esters have high saturation restricted their usages at low temperatures.
Several pour point depressants or cloud point reducer which available in the market are mineral based. In addition, they are normally suitable for mineral oil based liquid. Several pour point depressants are already known, U.S. Pat. Nos. 3,904,385 and 3,951,929, as well as corresponding German Application No. 22 64 328 describe the use of polymeric acrylates containing from 18 to 24 carbon atoms in the alcohol moiety. The disadvantage of these polymeric acrylates is that they have to be used in relatively high concentrations of from 0.01 to 3% by weight, based on the weight of the petroleum.
Copolymers of long-chain acrylic or methacrylic acid esters and 4-vinyl pyridine are described for the same utility in U.S. Pat. No. 3,957,659, as well as corresponding German Application No. 22 10 431 and in U.S. Pat. No. 4,110,283, as well as corresponding German Application No. 26 12 757. The copolymers in question are used in concentrations of from 200 to 2000 ppm. The disadvantage of these copolymers is that they are comparatively expensive because 4-vinyl pyridine is difficult to obtain on a commercial scale.
British Patent Specification No. 2,058,825, describe copolymers of long-chain acrylic acid esters, namely esters of “Ziegler-process” alcohols, and dimethylaminoalkyl acrylic acid esters or methacrylic acid esters for use as pour point depressants. Particular emphasis is placed on the shear stability of the products and also their effectiveness in concentrations of from 50 to 350 ppm. However, it is known that esters of the type in question (containing dialkylamino groups) can undergo hydrolysis in the presence of water, resulting in the formation of amphoteric, largely insoluble and hence ineffectual polymers. Finally, British Patent Specification No. 2,082,604, describe a copolymer of long-chain acrylates and maleic acid anhydride as a pour point depressant. The disadvantage of using this copolymer is that, because of their high reactivity, the anhydride groups are capable of further reacting to form acids which might possibly promote corrosion.